fix: convert cf-kv and excalidraw-libraries from submodules to regular files

- Remove stale cloudflare-worker submodule entry from .gitmodules
- Remove .git dirs from cf-kv and excalidraw-libraries so Git tracks them as regular files
- Fixes 'No url found for submodule path cf-kv' CI error

excalidraw-libraries/stats/2021-02/2021-02-02.json

@@ -0,0 +1,27 @@
+{
+  "dbssticky-data-viz": 25,
+  "drwnio-drwnio": 44,
+  "drwnio-storytelling": 33,
+  "dwelle-hearts": 7,
+  "excacomp-mobile-kit": 28,
+  "excacomp-web-kit": 51,
+  "franky47-apple-devices-frames": 11,
+  "g-script-android": 7,
+  "g-script-charts": 12,
+  "g-script-forms": 37,
+  "g-script-medias": 10,
+  "h7y-dropdowns": 15,
+  "inwardmovement-information-architecture": 31,
+  "jakubpawlina-graphs": 34,
+  "lipis-polygons": 7,
+  "lipis-stars": 6,
+  "maeddes-technology-logos": 46,
+  "marcottebear-raspberrypi-zero": 17,
+  "morgemoensch-gadgets": 8,
+  "newbyca-cryptocurrencies": 15,
+  "pclainchard-it-logos": 15,
+  "revolunet-raspberrypi3": 2,
+  "shinkim-presentation-templates": 16,
+  "youritjang-software-architecture": 87,
+  "youritjang-stick-figures": 36
+}